1. Field Of the Invention
The present invention relates to heads up display devices for moving vehicles such as automobiles and airplanes and particularly to such devices utilizing the vehicle's windshield to reflect an image to the observer.
It has long been recognized that the optimum display to the operator of a moving vehicle would be one which did not require the operator to shift his eyes from the external scene to observe his instrumentation. Such displays minimize the amount of time required for the operator to refocus his vision from one field to another and maximize his perceptability of the instrumentation. Optimum devices for this purpose have long been sought.
Existing devices directed to solving this problem employ high intensity light sources which generate light in the form of alpha-numeric characters to be displayed and reflect this high intensity light off of the vehicle's windshield, or a separate screen provided for that specific purpose. The problem associated with such methods is that ambient light external to the windshield is often brighter than the light source within the vehicle, thereby preventing or impairing the visibility of the display. Because of the extremely high intensity of light source required to overcome external ambient light levels, existing devices are impractical or inoperative under many conditions.